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Background: Pre-treatment serum lactate dehydrogenase (LDH) has emerged as prognostic factor for many cancers. In this study, we evaluated the value of LDH in predicting distant metastasis and poor survival for patients with nasopharyngeal carcinoma (NPC). Methods: Clinical data from 172 non-metastatic NPC patients were retrospectively collected and serum LDH levels were routinely measured before treatment. The independent-samples t test was used to calculate differences between serum LDH levels from the various patient groups. Receiver-operating characteristic (ROC) curve analysis was performed to select the optimal cutoff points. The Kaplan-Meier method and log-rank test were adopted to calculate and compare the distant metastasis free survival (DMFS) and overall survival (OS) rates. The Cox proportional hazards model was used to carry out univariate and multivariate analyses. Results: NPC patients progressed with distant metastasis often have higher pre-treatment serum LDH levels than those did not develop distant metastasis (mean LDH level was 237.1U/L and 108.8U/L, respectively, p=0.001). Elevated LDH level was identified as an independent prognostic factor for poor DMFS (hazard ratio (HR), 8.31; 95% confidence interval (CI), 2.44-28.32; p=0.001) and OS (HR, 4.45; 95% CI, 1.77-11.21; p=0.002). Moreover, subgroup analyses revealed significant associations between serum LDH level and worse survival in advanced stage patients. Conclusions: Pre-treatment serum LDH level can predict distant metastasis and associate with the poor survival in patients with NPC.

Marine oil shale from the Shenglihe oil shale section in the Qiangtang basin, northern Tibet, China, was dated by the Re-Os technique using Carius Tube digestion, Os distillation, Re extraction by acetone and ICP-MS measurement. An isochron was obtained giving an age of 101±24 Ma with an initial 187 Os/ 188 Os ratio of 1.84±0.11(n = 11, MSWD = 3.5). The Re-Os age agrees with the geological age derived from biostratigraphic data, indicating the great potential of the Re-Os method for dating the marine oil shale. Our new data (Bilong Co oil shale) also show that the samples must derive from the same layer of oil shales to determine an accurate and precise depositional age for the marine oil shale with the 187 Re- 187 Os radioisotope system.